Interpretive Summary: Nitrogen loss can be a serious problem to vegetable growers in flood prone areas. A greenhouse study was conducted to determine the effects of N fertilization on recovery from flood damage in green beans. There were three fertilizer treatments:1) normal - 2 N applied preplant, 2 applied at flowering, 2) liquid - daily liquid applications with irrigation water (fertigation), and 3) foliar - normal fertility treatment plus two foliar spray treatments applied after flooding. Plants were flooded to 1 cm above the soil surface for two or four days then allowed to drain and grow under normal greenhouse conditions. Flooding reduced shoot dry weight, leaf area, pod weight and number of pods produced below that of the controls for all except the 2 day liquid and 2 day normal treatments in the summer planting. Both these treatments had a leaf area, and with the 2 day liquid a DW greater than the controls. There were few significant differences in shoot dry weight, leaf area and pod weight between the liquid, foliar and normal fertility treatments. Where differences existed, and as a general trend with pod weight, the liquid out performed the normal and foliar fertility treatments. From planting through recovery from flooding (Day 45) the liquid fertility treatment tended to maintain chlorophyll levels either equal to controls or above those of the foliar and normal treatments. The liquid treatment tended to have a net photosynthetic rate higher than that of the other fertility treatments. Also, the liquid treatments recovered photosynthesis rates faster and to a higher level after flooding. The 2 day liquid treatment appeared to have a denser root system before flooding and maintained a dense root pattern through the recovery period. Also, this treatment had a greater leaf area before flooding than the other fertilizer treatments. Plants in the 2 day liquid treatment probably resisted flood damage longer and were in a better position to recover from injury. This likely resulted in the higher pod weight for the 2 day liquid fertility treatments. The precise role fertigation can play in mitigating adverse effects of flooding is not yet clear. Nevertheless, daily liquid fertility treatments (fertigation) may be an acceptable strategy to mitigate certain effects of flood damage to beans.

Technical Abstract:
Nitrogen loss can be a serious problem to vegetable growers in flood prone areas. A greenhouse study was conducted to determine the effects of nitrogen application method on recovery from flood damage in green beans (Phaseolus vulgaris). There were three fertilizer treatments:1) normal - ½ N applied preplant, ½ applied at flowering, 2) liquid - daily liquid applications with irrigation water, and 3) foliar - normal fertility treatment plus two foliar spray treatments applied after flooding. Plants were flooded to 1 cm above the soil surface for two or four days then allowed to drain and grow under normal greenhouse conditions. At harvest there were few significant differences in physical characteristics between the fertility treatments. However, the liquid treatment tended to out perform the normal and foliar fertility treatments. From planting through recovery from flooding (Day 45) the liquid fertility treatment tended to maintain chlorophyll levels either equal to controls or above those of the foliar and normal treatments. The liquid treatment tended to have a net photosynthetic rate higher than the other fertility treatments and recovered faster and to a higher level after flooding. The 2-d liquid treatment appeared to have a denser root system and a larger leaf area, these plants probably resisted flood damage longer and were in a better position to recover from injury. This likely resulted in the 2-d liquid producing a higher pod FW than the other treatments. Daily liquid fertility treatments (fertigation) may be an acceptable strategy to mitigate certain effects of flood damage to beans.
Abbreviations: DAP-days after planting; FW-fresh weight; DW-dry weight